I'm a Fellow at the Adam Smith Institute in London, a writer here and there on this and that and strangely, one of the global experts on the metal scandium, one of the rare earths. An odd thing to be but someone does have to be such and in this flavour of our universe I am. I have written for The Times, Daily Telegraph, Express, Independent, City AM, Wall Street Journal, Philadelphia Inquirer and online for the ASI, IEA, Social Affairs Unit, Spectator, The Guardian, The Register and Techcentralstation. I've also ghosted pieces for several UK politicians in many of the UK papers, including the Daily Sport.

Climate Change: Not as Bad as We Thought it Was Going to Be

Unlike many of my fellow right wingers I’m generally in agreement with the science of climate change. My disagreements come ion only two places. The first is over what we do about it assuming it really is all true but that’s something for another time. The second is that the one thing we still don’t know is “what is climate sensitivity?”

And this is a very important point indeed. What we want to know is how much will temperatures change if we double the amount of CO2 in the atmosphere? That’s what we generally mean by that climate sensitivity. If the temperature change is 0.1 oC then we’ve precisely nothing at all to worry about and we can all start burning as much coal and petrol as we like.

If the answer is 20 oC then we’ve got a huge problem and we might start thinking about capital punishment for those who burn oil or coal.

Now we are pretty sure about what direct climate change from a doubling of CO2 will be: some 0.7 oC. This isn’t a massive problem and trying to worry about it or solve it probably justifies spending a few tens of billions a year on looking into alternatives to oil and coal. But not the hundreds of billions being thrown around and most certainly not the absurd attempts to close down industrial civilisation that some demand.

But, and here’s the problem, we don’t really know all that much about the feedbacks. Maybe that warming by 0.7 oC will melt some of the arctic snow which means less sunlight will be reflected back into space meaning that more snow will melt and…..or maybe the oceans will warm, the methane clathrates bubble up and…..and the same is true on the other side. We’re not really sure whether higher CO2 will lead to more plant growth and thus lower CO2 in the atmosphere. Or maybe more carbon trapped in soils.

We know that there are a number of these feedbacks, we’re pretty sure which direction each of them works in individually, but we’re pretty unsure about what the effect of adding them all up is. Which is what we call climate sensitivity, that total effect of all of the feedbacks (please note, a very important point. Climate sensitivity is all of the effects: we don’t get to some point and then have runaway climate change. If cs is 2 oC then that’s all the warming we get). Which is what makes this paper, by Schmittner et al, so interesting:

Assessing impacts of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 K as best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small but significant chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K 66% probability). Assuming paleoclimatic constraints apply to the future as predicted by our model, these results imply lower probability of imminent extreme climatic change than previously thought.

Now whether this answer is actually correct or not is another matter. Here’s another scientist in the field discussing the paper. The general conclusion of which is “hmmm”. But then that’s how science works, present your results and your workings and then see who agrees or does not.

This is however the most important remaining question in the science of climate change. Not is it happening, but how bad is it going to be? The lower climate sensitivity is the less bad it will be and the less attention we have to pay to it.

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